Author Topic: 10mm Evo Project.  (Read 887 times)

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Offline Obiwan

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Re: 10mm Evo Project.
« Reply #30 on: January 10, 2019, 08:38:34 PM »
Heavier springs will still help keep the bolt closed longer too.

But when the spring is uncompressed state, you don't have that much force resisting chamber pressures. It's the inertia in the bolt (caused by its mass) that is important for the tiny but important delay in movement. It needs to be overcome at the beginning of gas expansion. Think of high resisting force at the beginning, then decreasing force as the bolt is in motion (because, after all, you want it to travel). A spring has low resisting force at the beginning which then increases as the spring gets compressed. That's a completely different force profile. A spring safe enough might be so stiff that the bolt won't even travel enough to extract the cartridge.

Offline X16191

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Re: 10mm Evo Project.
« Reply #31 on: January 10, 2019, 08:43:07 PM »
I understand the  points you make mate.

This is why there will be testing. And if I need to add weight there is options to that. Granted it would need to remain in check not to make  unnecessary  wear in some areas.  But again will come in time.


9mm sammie psi is  35,000 psi
9mm+p is 37,500 psi

10mm is 37,500 psi

Overall I dont see a massive difference that said. Its character ging the intended use of the evo.  And with that comes risk and possible danger. And that said safety is 1st AMD for most. And I dont take my personal safety lightly. I have not melted over 10 +TONS of lead without being safe.

Again I am going to try to take everything I can I consideration while doing this project.

I currently run AR15's at close to 60k PSI safely( not a normal 556 bolt)

But I push a 7mm 140grain at 2750 fps and a 168grain at 2550 FPS again AR15 wildcat.

Also run a 55grain .224 at 4000 FPS and assorted other cats at again 58k plus PSI in the AR15 safely again this took time to get going. I was not the soul tester and worker of this was a group of us.

But this is not my 1st time wildcatting  just a bit of background on me boss.

That said I'll look at the math and figure out weight ratios and such. And keep this updated with such details.



Offline Obiwan

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Re: 10mm Evo Project.
« Reply #32 on: January 10, 2019, 09:08:45 PM »
Even if the pressures of 9mm+p and 10mm are the same, the 10mm bullet weighs more, even if a seemingly small amount. That's additional inertia that requires more force. That same additional force will be directed at the bolt, causing the bolt to move sooner/easier, affecting timing.

If I were you, I would plan on needing to add weight to the bolt. (From reading that web site mentioned earlier, it seems like you need to "bolt-on" an additional pound). But I'm reasonable sure you need to dial it in by test firing, so rather than making several bolts to try, maybe there's a way to literally bolt on weight. I would start with more weight and work my way down if required. Anyway, you gotta take it into account. Your initial post didn't list considerations of bolt and spring weight, which is what prompted my posting.

Either way, sounds like a cool project. Hopefully we could increase the physics/geek-factor of the equation with these posts. :)  If it all works out, I bet you'll have people drooling over the 10mm Evo. And perhaps a shop might want to work with you and your design to actually make drop-in replacement barrel and bolt parts.

Please keep us posted in the project!
Cheers!

Offline John A.

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Re: 10mm Evo Project.
« Reply #33 on: January 10, 2019, 09:51:34 PM »
I was going to post some chamber pressure numbers too.  I'm not discrediting any reservations that anyone has had.

I think 9mm nato is around 37,500-38k

I'm currently shooting 165 gr bullets in my 9mm and I'm certain the suppressor adds more back-pressure too.

I'm also currently loading 165 gr XTP bullets in my 40 caliber too.

I'm not saying for anyone to proceed blindly, but I don't think the pressure on the bolt is going to be much more noticeable either.  Especially with a heavier spring.
When people ignorant of guns make gun laws, you end up with ignorant gun laws.

Offline X16191

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Re: 10mm Evo Project.
« Reply #34 on: January 10, 2019, 10:04:28 PM »
It would be fairly easy to ass weighttobe honest could millout a small area pour some lead.  And bolt a nice little cover over it.  So that's not to bad.

Lots of optionsbut 1st need to see if I can safely mod the slide and keep it strong.

2nd will be mag options 3rd slide and spring

Offline Azrckcrawler

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Re: 10mm Evo Project.
« Reply #35 on: January 11, 2019, 08:58:57 AM »
What you guys are missing is the bolt face difference between 9mm and 10mm.  Read the article I linked to and when you understand the text you can plug in your 9mm load data to the excel sheet it has linked.  Even with a heavy 165gr 9mm load you don't come near the bolt mass required for the heavy 10mm loads.

FWIW I am a huge 10mm fan.  I learned all this the hard way after buying an off the shelf $1800 blowback 10mm and after months of messing with it came to realize that there was no way to get enough weight in the bolt/buffer system for it to work safely.  Even after 50 or so case head separations the mfg claimed it was safe.  Read all about it here - http://10mm-firearms.com/10mm-rifles/tactical-edge-rd-10-review/

The only blowback 10mm I have used that worked well was an Aero Survival rifle.  It uses a custom upper that allows for a really heavy bolt.  I believe it was 2.8lbs which is marginal according to the calcs (the spreadsheet assume a slight overcharge).  I did measure swollen cases on the heavier 10mm loadings, mostly 200-220gr WFNGC projectiles.



Offline X16191

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Re: 10mm Evo Project.
« Reply #36 on: January 11, 2019, 10:58:47 AM »
Most the 10mm I run is 180 185 grain and under but yes I look at tings.

 

anything